title: Estradiol binding by intact cells isolated from DMBA-induced mammary tumors of the rat.
abstract: Study of hormone binding in intact cells enables one to examine binding under conditions which elicit a biological response. Cells from 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumors of the rat were enzymatically dispersed. More than 80% of these cells excluded trypan blue and were used to study binding of [3H] estradiol-17 beta. Specific binding was determined by subtracting the amount of [3H]estradiol bound in the absence and presence of 200-fold excess unlabeled estradiol. Specific binding at 37 degrees was maximal after 15 min. Steroid competition studies indicated that [3H]estradiol binding sites were relatively specific for estrogens, although there was a 9-18% inhibition of binding by androgens and progestins when present at 150-fold molar excess. Scatchard analyses of [3H]estradiol (0.15-5.0 nM) binding by whole cells suggest a single, high-affinity binding site (Kd = 7.5 x 10-10M) of low capacity (6.1 fmol/10(6) cells). More [3H]estradiol was translocated to the nucleus after 1 hr at 37 degrees than at 0 degrees. Preliminary studies indicated that incubations at 37 degrees result in appreciable metabolism of [3H]estradiol to other steroids and/or conjugates when examined by silica gel thin layer chromatography.
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene; D000230:Adenocarcinoma / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism*; D051381:Rats; D013379:Substrate Specificity
chemical_list: D004958:Estradiol; D015127:9,10-Dimethyl-1,2-benzanthracene